The invention pertains to a record carrier storing at least video-related user data and control data in digital form, which control data enable playback control of the user data, which control data comprises at least play control data which defines user data items which are playable, at least selection control data for enabling the user to select and control reproduction of user data and at least variable control data for operating on user and system variables.
The invention further pertains to an apparatus capable of reproducing user-data under control of control data, the user data and the control data being stored in digital form on a record carrier, which user data comprises at least video data, which control data comprises at least play control data which defines user data items which are playable and at least selection control data for enabling the user to select and control reproduction of user data items, which control data further comprise variable control data defining operations on user and system variables, which apparatus is provided with control means comprising a processor controllable by said control data.
The invention further pertains to a method of reproducing user-data under control of control data, according to which method the user data and the control data are read from a record carrier on which these data are stored in digital form, which user data comprises at least video data, which control data comprises play control data, selection control data and variable control data, according to which method user data items are played under control of the play control data, according to which method the selection control data enables the user to select and control reproduction of user data items, according to which method the variable control data control operations on user and system variables.
Such a record carrier, apparatus and method are known from WO 98/09290. The play control data in the form of Play Lists enables the record and/or playback device to reproduce the user data in a predetermined order. Apart from video data, the user data may contain for example audio data, and data giving information about the video and/or audio data. The selection control data, in the form of Selection Lists enable the user to make a selection out of the available Play Lists by giving input to the apparatus. In addition the known apparatus can process variable control data by performing arithmetical operations and logical tests. The variable control data enables the apparatus a further way of controlling the playback of user data at the record carrier dependent of the history of user input.
In the known record carrier the variable control data comprises a Statement List which describes operations on variables and a Conditional List which describes conditional jumps.